Question

Problem 9.106 using varaiable specific heat assumption (Non-Ideal Regenerative Brayton Cycle)

9-105 A gas turbine for an automobile is designed with a regenerator. Air enters the compressor of this engine at 100 kPa and 30°C. The compressor pressure ratio is 8; the maximum cycle temperature is 800°C; and the cold airstream leaves the regenerator 10°C cooler than the hot airstream at the inlet of the regenerator. Assuming both the compressor and the tur- bine to be isentropic, determine the rates of heat addition and rejection for this cycle when it produces 115 kW. Use constant specific heats at room temperature. Answers: 240 kW, 125 kW Heat exchanger W - o Comb. Compressor Turbine FIGURE P9-105 9-106 Rework Prob. 9–105 when the compressor isentropic efficiency is 87 percent and the turbine isentropic efficiency is 90 percent.

Answer 1

A Given daila opressure at inlet of compressor Pi = 100kpa Temperature at inlet of compressor = Ti = 30 +2.43 -3034 Hind Tena Peroture at inlet of Turbine- TH = 800+ 2.73 >10756 Tos diagro るる Bentropic compression (1-2) T1 21 pressure ratio = 8 7 / 2 = ( 2 Is code - (s)* 1911393 .ts = 584.4522. * Efficiency of compressen Con Isantropic work : Real horn 0.87 · 584.85- 303 Tz! - 303 1. Ta'= 626.96 K 4-5_Process: e) a 1973 - 6) * 0.4 T5 - 582.49 K

(3)in. , Real 10031K Nexshoia molt 0.90 107) - T5 1073 - Bike 59 2.49 15 - Albania 640.541 K. IC Enorgy balance - To - Ta'a Tis To B-T' [5 - CT3-8) T3 - 626.96= 592.49 -T378 Ts = 613K Heat transfer in generator (or addition a generate - Cp Co Ty - Ty) = 1.005 (1073 - 613) = 462-3 KJ/kg Heat rejection are section = Cp (Tg-ti). -1-005 (592-49-303) > 290.93 KJ/K9